AimsTransducer and activator of transcription-3 (STAT3) plays an important role in tumor cell invasion and metastasis. The aim of the present study was to investigate the effects of STAT3 knockdown in nude mouse xenografts of pancreatic cancer cells and underlying gene expression.MethodsA STAT3 shRNA lentiviral vector was constructed and infected into SW1990 cells. qRT-PCR and western immunoblot were performed to detect gene expression. Nude mouse xenograft assays were used to assess changes in phenotypes of these stable cells in vivo. HE staining was utilized to evaluate tumor cell invasion and immunohistochemistry was performed to analyze gene expression.ResultsSTAT3 shRNA successfully silenced expression of STAT3 mRNA and protein in SW1990 cells compared to control cells. Growth rate of the STAT3-silenced tumor cells in nude mice was significantly reduced compared to in the control vector tumors and parental cells-generated tumors. Tumor invasion into the vessel and muscle were also suppressed in the STAT3-silenced tumors compared to controls. Collagen IV expression was complete and continuous surrounding the tumors of STAT3-silenced SW1990 cells, whereas collagen IV expression was incomplete and discontinuous surrounding the control tumors. Moreover, microvessel density was significantly lower in STAT3-silenced tumors than parental or control tumors of SW1990 cells. In addition, MMP-7 expression was reduced in STAT3-silenced tumors compared to parental SW1990 xenografts and controls. In contrast, expression of IL-1β and IgT7α was not altered.ConclusionThese data clearly demonstrate that STAT3 plays an important role in regulation of tumor growth, invasion, and angiogenesis, which could be act by reducing MMP-7 expression in pancreatic cancer cells.
Vascular smooth muscle cells (VSMCs) play a central role in the progression of atherosclerosis, where they switch from a contractile to a synthetic phenotype. Because of their role as risk factors for atherosclerosis, we sought here to systematically study the impact of matrix stiffness and (hemodynamic) pressure on VSMCs. Thereby, we find that pressure and stiffness individually affect the VSMC phenotype. However, only the combination of hypertensive pressure and matrix compliance, and as such mechanical stimuli that are prevalent during atherosclerosis, leads to a full phenotypic switch including the formation of matrix-degrading podosomes. We further analyze the molecular mechanism in stiffness and pressure sensing and identify a regulation through different but overlapping pathways culminating in the regulation of the actin cytoskeleton through cofilin. Together, our data show how different pathological mechanical signals combined but through distinct pathways accelerate a phenotypic switch that will ultimately contribute to atherosclerotic disease progression.
During podosome formation, distinct phosphatidylinositol 3,4,5-trisphosphate lipid (PI(3,4,5)P3) production and F-actin polymerization take place at integrin-mediated adhesions. Membrane-associated actin regulation factors, such as myosin-1, serve as key molecules to link phosphatidylinositol signals to podosome assembly. Here, we report that long-tailed myosin-1e (Myo1e) is enriched at the ventral layer of the podosome core in a PI(3,4,5)P3-dependent manner. The combination of TH1 and TH2 (TH12) of Myo1e tail domains contains the essential motif for PI(3,4,5)P3-dependent membrane association and ventral localization at the podosome. TH12 KR2A (K772A and R782A) becomes dissociated from the plasma membrane. While F-actin polymerizations are initialized from the ventral layer of the podosome, TH12 precedes the recruitment of N-WASP and Arp2/3 in the initial phase of podosome formation. Overexpression of TH12, not TH12 KR2A, impedes PI(3,4,5)P3 signaling, restrains F-actin polymerization, and inhibits podosome formation. TH12 also suppresses gelatin degradation and migration speed of invadopodia-forming A375 melanoma cells. Thus, TH12 domain of Myo1e serves as a regulatory component to connect phosphatidylinositol signaling to F-actin polymerization at the podosome.
Our goal was to determine the roles and regulatory mechanism of microRNA-935 (miR-935) in the progression of pancreatic cancer. The results showed that, compared with normal pancreatic tissues and cells, the expression of miR-935 was markedly upregulated, while INPP4A expression was obviously downregulated in pancreatic cancer tissues and PANC-1 cells. After transfection with the miR-935 inhibitor, miR-935 was significantly suppressed, and suppression of miR-935 significantly inhibited cell proliferation, suppressed cell migration, and induced cell apoptosis of pancreatic cancer cells. Moreover, suppression of miR-935 resulted in a significant increase in the expression of p27. Also, suppression of miR-935 resulted in significant expression changes of EMT markers; E-cadherin was significantly upregulated, while N-cadherin, Snail, and vimentin were markedly downregulated. In addition, after suppression of miR-935, the expression of apoptosis-related proteins was also changed; Bax was significantly upregulated while Bcl-2, procaspase 3, and active caspase 3 were obviously downregulated. Importantly, opposite effects were obtained when miR-935 was overexpressed by transfection with the miR-935 mimic. In addition, INPP4A was a direct target of miR-935. Silencing of INPP4A significantly counteracted the effects of miR-935 suppression on cell migration and apoptosis, as well as the expression changes of the above EMT- and apoptosis-related molecules. Our findings indicate that upregulation of miR-935 may promote pancreatic cancer cell proliferation and migration and inhibit cell apoptosis by targeting INPP4A. miR-935 and INPP4A may serve as potential targets in the therapy of pancreatic cancer.
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